This article presents a new and sensitive method for the determination of trace amounts of fungicide carbendazim by dispersive liquid–liquid microextraction (DLLME) combined with UV–vis spectrophotometry. The method is based on the reduction of Fe(III) to Fe(II) by carbendazim, its reaction with potassium ferricynide to form a blue product and extraction into CCL4 by DLLME technique using methyltrioctylammonium chloride (Aliquat 336) as a disperser agent. Under the established optimum conditions, the calibration graph was linear in the range of 5–600 ng mL−1 of carbendazim with a limit of detection of 2.1 ng mL−1. The relative standard deviations for eight replicate determinations of 50 and 300 ng mL−1 of carbendazim were 3.9% and 1.0%, respectively. The proposed method was successfully applied to determination of carbendazim in soil and water samples.